Sneaky problem fixed: rough idle, bad MPG, low power

camelman · Oct 9, 2015

I've been struggling with my 1996 ranger 2.3 5-speed since I bought it. Every change I made to it has improved it, but something has been wrong since I changed my spark plug wires. I think I finally got it today. I found a few loose bolts on the intake manifold holding the intake to the head. They were for the rear cylinder. What an unbelievable difference! I actually like this truck now!!

The bolts must have worked themselves loose on their own. The engine was untouched when I got it at 165k miles, so I changed the timing belt, plugs and wires for the first time. The wires were stuck tight on the plugs and I ripped a few plugs in half pulling the wires off. I braced against the intake manifold when pulling the wires off to get leverage, and that pushing must have created a leak due to the loose bolts. Anyway, it's fixed now. I didn't change the gaskets, although I'm sure that would be the icing on the cake. If you're experiencing a stumble, bad MPGs, or low power, then it wouldn't hurt to check your intake manifold bolts.

Camelman

Mark_88 · Oct 9, 2015

Good to know...did you get a CEL with a P0351 DTS code?

That's what I've got right now and it wouldn't surprise me if the intake was loose...previous owner replaced the 2.3 with a 2.5 about five years ago and I haven't looked at that aspect of it yet...

camelman · Oct 9, 2015

I never got a CEL, although I did see a large number of misfires. Not enough misfires to throw a code though.

Mark_88 · Oct 9, 2015

OK, thanks for the feedback. The P0351 (the 1 represents cylinder 1) has been known to be caused by vacuum leaks or things like loose manifolds and can be very hard to track down in some cases.

I'm still waiting for nice weather to tackle this one because it may require a bit of part swapping...

Dprocks100 · Oct 9, 2015

Good to know, been trying to find my rough high idle, misfire situation for the last 2 weeks. One more thing to check out.

camelman · Oct 9, 2015

Here are a couple things I found while working on it:

~ you can access this area even with a hot engine, just try not to touch the oil filter
~ there are a few long studs that have plastic organizing hooks for wires and vacuum lines that snap on after the nuts are tightened. They pop off easily and go back on easily, so don't skip them
~ there are two fasteners for each runner, and I recommend checking each fastener
~ I found one loose fastener between the two intake manifold sections also
~ I needed a 13mm wrench for one nut, but could reach all of the others with some combination of a 6" extension, 3" extension, deep well sock and regular socket
~ the front-most nut is behind an engine hoist bracket and I haven't checked it yet. I think it can be checked without removing the engine hoist bracket simply by loosening the corresponding nut that holds on the bracket, and then using a wrench to access the inner nut

Good luck and please post your findings!

Camelman

bobbywalter · Oct 9, 2015

ya know....one of the first things i use is a vacuum gauge, and i always pull the fill cap and observe the situation with and without the airfilter in situ on a drivability complaint.

leaking valves/weak springs and small coolant combustion leaks cause all sorts of issues codes wont necessarily ever catch. and there are several situations where you can have a vacuum leak and not know it on a gauge as well.

thanks for the report, as it puts the reason soundly for the basic measures.

camelman · Nov 23, 2015

If you guys didn't notice my other post, I think I found the main reason for my troubles. The previous owner rolled the odometer back about 150,000 miles!!! No joke! That's more than most cars ever travel. Total estimated mileage is 350,000.

Anyway, it's running well. Will look better after I get the rear end straightened out after the uninsured driver rear ended me.

camelman · Apr 4, 2017

It's been a while since I updated this thread, and I want to consolidate what I've found, so here's an update.

I replaced the engine mounts and the trans crossmember and a lot of the engine operational issues I was experiencing went away. It seems that the engine was shifting so much that it seemed that it was running rough.

About 8 months after replacing the mounts I had the cat replaced too ($350 or so for that work at a shop). That really cleared things up and the truck runs incredibly well now with power immediately available off idle and a much more responsive engine. I get in the mid 20s on the highway for MPGs, and driving slower on Sierra Nevada mountain roads I've gotten 32 MPG!!

I don't have any other operational issues now that I'm at all concerned about aside from the ABS light. However, even in the wet, I can't get my new rear tires to break free when I brake hard, so not having rear ABS doesn't seem to be the biggest of issues.

Actually, there's one more. My third brake light is leaking and I actually had grass growing inside the truck this winter! That was hilarious to find. I tried caulking and sealing the light, but the leak seems to be through the plastic itself. I found some lights for $45 on amazon, so I'll likely get one of those.

Camelman

Mark_88 · Apr 4, 2017

camelman said:
...and I actually had grass growing inside the truck this winter! That was hilarious to find.

Haha...I once pulled an otherwise mint carpet out of another Ranger and it had a nice crop of grass growing in a puddle of water from having no windshield...it turned out to be the best carpet I ever mowed...

camelman · Jun 28, 2017

Mark_88 said:
it turned out to be the best carpet I ever mowed...

Classic!

Little update on Rupert (my truck). It's running like a dream still, and I loaded it up with two dirt bikes in the bed and a third on a hitch-mounted carrier. The extended cab was filled to the brim, and my girlfriend and I hopped in for a weekend trip with some friends. The truck never skipped a beat even in 100+ heat, and got over 20MPG.

Mileage estimate is around 375K now. Gonna be sad when I let this truck go.

Camelman

Sneaky problem fixed: rough idle, bad MPG, low power

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